2022-June-14 - Prerelease - 2.6.900

Infra: clean up postgres deployment role (#10636)

- Remove the password for the 'postgres' user. The 'postgres' user
will be able to access database only after a person has logged into
the OS, we can avoid having a password on that account and instead
authentication is done at an OS level. This does not impact the
application database users.

- Remove 'set password hack', password for application users is
seemingly now properly set.

- Remove usage of deprecated ansible modules by using instead
'postgresql_privs'